You should open the files test-all-constraints-official.fet, test-all-constraints-mornings-afternoons.fet,
test-all-constraints-block-planning.fet, and test-all-constraints-terms.fet from FET (with the language set to your language)
and check the all time constraints and all space constraints dialogs, the description and detailed description for each
constraint should look good.

Constraints should be different one from the other, for instance same starting time and same starting hour, or preferred
starting time (for a single activity), preferred starting times (for a single activity, for a set of activities and for a
set of subactivities) and preferred time slots (for a single activity, for a set of activities and for a set of subactivities).
Please make sure all these kinds of constraints are clearly separable one from each other.

These files are not solvable, they just contains all constraints.
